1. Field
Aspects of the present invention relate to a flat panel display device, and more particularly, to a flat panel display device having an improved encapsulation structure for preventing permeation of moisture from an external environment, and an encapsulation substrate for forming the encapsulation structure.
2. Description of the Related Art
Flat panel display devices such as organic light emitting display devices may have a thin and flexible structure, and thus, much research has been conducted for further development thereof. An organic light emitting display device includes a light emission unit that may deteriorate due to permeation of moisture. Thus, an encapsulation structure is needed for sealing the light emission unit to prevent permeation of moisture from an external environment.
In most typical encapsulation structures, a light emission unit is formed on a glass substrate. An encapsulation substrate is formed of the same glass material as the glass substrate and covers the light emission unit. A sealant is sealed between the glass substrate and the encapsulation substrate.
For example, a sealant such as an ultraviolet curing agent is coated on a glass substrate around a light emission unit. The glass substrate is covered by an encapsulation substrate. Then, an ultraviolet ray is irradiated to cure the sealant, thereby obtaining a sealing structure.
However, a vapor permeability resistance of a general sealant is greatly reduced in time, and thus its sealing effect subsides. Accordingly, in order to constantly maintain a sealing effect, a new sealing structure having excellent vapor permeability resistance is required.
Also, as current flat panel display devices have a large screen obtained by using a large surface area, a light emission unit having a large surface area may generate a great deal of heat. However, since a typical glass substrate and an encapsulation substrate are formed of only a glass material that has a low heat transfer speed, heat radiation may not take place appropriately. Thus, deterioration in performance of a product may occur if overheating is continued for a long time.